1. Field of the Invention:
This invention relates to flexible polyurethane foam compositions and more particularly to compositions having a low flame spread index in ASTM test E-162-76.
2. Description of the Prior Art:
Flexible polyurethane foam is employed as upholstery cushioning material, for example, in the manufacture of armrests, instrument panel surfaces, seating materials, et cetera for aircraft, automobile and truck bodies. In general such upholstery cushioning may be "integral skin foam" which is prepared with a halogenated blowing agent, or "seating foam" which is a high resiliency flexible foam usually prepared with water as a blowing agent. For some installations, such upholstery cushioning material must exhibit a flame spread index less than 150 (arbitrary ratings) in ASTM test E-162-76. The prior art polyurethane foam compositions will not pass that test although, when covered with suitable fire-retardant upholstering materials (such as polyvinyl chloride films), the combination has been successful. Apart from the present composition, there are no known integral-skin, flexible polyurethane foam compositions which will pass the ASTM test E-162-76 with a rating less than 150. Thus the polyurethane foam compositions with a flame spread less than 25 are particularly unexpected.
In our copending patent application Ser. No. 930,412, the benefits of the present invention as applied to integral skin flexible polyurethane foam were described. Subsequently we have discovered that these same benefits can be obtained with cushioning foam, i.e., polyurethane foam having a high resiliency which is blown with water. We have been able to obtain flame spread ratings less than 25 under the ASTM Test E-162-76 with water blown flexible polyurethane foam compositions.
Many fire-retardant additives are known for use in polyurethane foam compositions. Pentabromoethyl benzene, the material employed in the present compositions, is known as a fire-retardant additive to polypropylene, polystyrene, ABS resins, polymethyl methacrylate.